Nonspecific resistance to infection expressed within the Peyer's patches of the small intestine.

Intraperitoneal or intraduodenal pretreatment of mice with dead Corynebacterium parvum failed to produce significant nonspecific resistance to Salmonella enteritidis infection in the Peyer's patches of the small intestine. However, mice pretreated with a single oral infection of live Listeria monocytogenes were capable of restricting the growth of S. enteritidis in the Peyer's patches. The ability of L. monocytogenes to induce nonspecific resistance was associated with the ability of this organism to cause an increase in the number of macrophages in the Peyer's patches.